Other - about 7 cases in 100,000 have no known cause attributed to them.

Being exposed to radiation is a known cause of cancer.

On the medical side the doctors said there was no known cause.

Hypertension is a complex disease, with no known single cause.

Most of the cases that occur at an older age have no known cause.

There is no known cause for this type of hair loss.

However, there was no known cause which could be responsible.

However, 60% of cases do not have a known cause.

In most cases, there's no known cause for this condition.

As of 2012, there is no known cause or cure.